Render preview window when the initial query fails to match

Only if preview template contains {q}

Fix #1452
Related #1307

src/terminal.go

@@ -1533,7 +1533,7 @@ func (t *Terminal) Loop() {
 
 	go func() {
 		var focused *Item
-		var version int64
+		var version int64 = -1
 		for {
 			t.reqBox.Wait(func(events *util.Events) {
 				defer events.Clear()